fix(random-mix): keyword blocks and scoped genre list on Build a Mix (#965)

* fix(random-mix): honor keyword blocks and scope genre list to library

Keyword filter was gated behind the audiobook exclusion checkbox, so
blocked artists still appeared after Remix. Genre Mix now loads genres
via fetchGenreCatalog (scoped index / library filter) instead of raw
getGenres; show empty state when all tracks are filtered out.

* docs(changelog): credit zunoz on Psysonic Discord for PR #965

src/components/randomMix/RandomMixGenrePanel.tsx

@@ -6,6 +6,7 @@ interface Props {
   isMobile: boolean;
   genreMixExpanded: boolean;
   setGenreMixExpanded: React.Dispatch<React.SetStateAction<boolean>>;
+  genresLoading: boolean;
   serverGenresLength: number;
   displayedGenres: string[];
   allAvailableGenresLength: number;
@@ -18,7 +19,7 @@ interface Props {
 
 export default function RandomMixGenrePanel({
   isMobile, genreMixExpanded, setGenreMixExpanded,
-  serverGenresLength, displayedGenres, allAvailableGenresLength,
+  genresLoading, serverGenresLength, displayedGenres, allAvailableGenresLength,
   selectedGenre, genreMixLoading, onSelectAll, onSelectGenre, onShuffle,
 }: Props) {
   const { t } = useTranslation();
@@ -43,9 +44,9 @@ export default function RandomMixGenrePanel({
         <div style={{ marginTop: isMobile ? '0.75rem' : 0 }}>
           <p style={{ fontSize: 12, color: 'var(--text-muted)', marginBottom: '0.75rem' }}>{t('randomMix.genreMixDesc')}</p>
           <div style={{ display: 'flex', flexWrap: 'wrap', gap: '0.4rem', alignItems: 'center' }}>
-            {serverGenresLength === 0 ? (
+            {genresLoading ? (
               <div className="spinner" style={{ width: 14, height: 14 }} />
-            ) : displayedGenres.length === 0 ? (
+            ) : serverGenresLength === 0 || displayedGenres.length === 0 ? (
               <span style={{ fontSize: 12, color: 'var(--text-muted)' }}>{t('randomMix.genreMixNoGenres')}</span>
             ) : (
               <>